Pin tumbler lock



July 6, 1954 w. D. KOTAB 2,682,764

PIN TUMBLER Loox Www Filed April 28, 1951 2 Sheets-Sheet 1 2W ff' 'g' X0 a 2.9 2f

, Y grigi/gy IUI l, ff f ,Q'g' 1| 4|" 27 4 IIIIIIIIIIIIII ff 20 f5 67 WARkE/v 0. Koma,

"X9 IN V EN TOR.

A 7' TORNEK July 6, 1954 w. D. Ko'rAB 2.682,764

PIN TUMBLER Locx l WARREN D. Koma,

INVENTOR.

A TTORNEK Patented `luly 6, 1954 UNITED rSTATE if;

esatti fUF F ICE Claims.

,-...This ,inventionfrelates .to locks of the Din tumbler type in which locking pins or tumblers .are slidably mounted in two sets of pin bores,

one ofthe sets of bores being Ain a stationary lock cylinder and the other set y-beingin a cooperating .plug rotatably mounted-insidethe xed cylinder. When the matching key is inserted into a keywayvleading into the interior of the plug, the locking pins are shifted to position the ends of the pins in alignment with the circumferential surface of the plug whereby the plug is released for lock-actuating rotation.

' -While locksof this! type are well regarded as is evident in their wide use, it is a fact, nevertheless, that they can be opened without the t use of a key. It is' often not too diicult to pick a pin'tumbler lock of theprevailing type simply by exerting a slight turning pressure on the plug and simultaneously applying a suitable instru- Vrnentthrough the keyway to manipulate the looking pins.

The present inventionis directed especially to the'problern of Yconstructing 'such a lock in a -manner to make unauthorized tampering extremely difcult'if not'to make the lock completej ly' pick-prooi. -This'problem is :met by a unique keyway 'from arst key-receiving configuration 'to a'second 'coniiguration' and vvice versa. 'first keyway'fconnguration provides a simple straight passage into the region of the ylocking 'pins and the second coniguration provides a The tortuous and more'restricted passage that makes "the inner region'of the llocking pins accessible vonly with extreme diiiiculty.

y Incorporated-in this arrangement is a suitable guard element controlled by relative movement 'of'itheJkeyway-forming parts in such manner thatlthe guard element automatically cuts off the keyway from the locking pins whenever the keyway assumes the rst .mentioned configuration vof` a simple straight passage. l pins are protected from tampering by the auto- Thus, the locking matic guard element whenever the keyway is relatively openandat other .times the locking pins are protected by the tortuousness of the keyway itself.

The key matching the lock is inserted'when the'keywayhas'the first congurtion of a straight passage and then the conguration is changed to the tortuous coniiguration whereupon the automatic guard element automatically shifts position to make the locking pins accessible for operation bythe key. It is apparent that to make this mode of operation possible the two keyway coni'igurations must have portions in common. In other words, there must be a portion of the passageway that'does not change in the shift from one conguration to the other and the key must conform to this Yunchanging portion.

In the preferred practice of the invention the keyway is formed in part by a body xed to the rotatable plug andinpart by'what may be termed a*v guard member that is rotatably mounted adjacent the plug and 'preferably coaxial therewith. The` plug and the associated body, which body may be an integral part of the plug, are concealed by the guard'member. The guard member extends to the exrior ofthe lock and is adapted for convenient -'manual manipulation to change the conguration ofthe keyway.

The variousY features and advantages of the invention may be understood from the following detailed description taken with thev accompanyingV drawings.

In the drawings; which are to be regarded as merely illustrative,

Figurey1 is a' perspective view of a preferred embodiment of the-lock as seen from the front and side;

` Figure 2 is an enlarged vi-ew of the lock partly insection and -partly in perspective; l

Figurer-3 isfa perspective view on the same scale ofthe guard member as seen from the side and rear; v

`Figure exis alongitudinal sectional View of the lock with the parts positioned to give the keyway its rst or key-receiving coniguration;

Fig; 5 is a transversesection taken as indicated bythe line 5-5 of Figure fi;

Figure 6 is 'an 'enlarged fragmentary sectional view showing "the locking pins or tumblers atY the-invention shown in the drawings include'a cylindrical housing or..Xed.lock cylinder It, a

plug il rotatably housed in the lock cylinder, a circular body I2 ixedly mounted inside the plug I I, and what may be termed a guard member I3 that is rotatably mounted adjacent the plug and carries a guard elem-ent I4 in the form of a curved blade.

The cylindrical housing or xed lock cylinder III may be or" any suitable construction adapted for mounting in a door or the like. In the construction shown the lock cylinder I has an inner cylindrical wall I 8 and a front wall I9 with a circular opening therein. At the top of the inner cylindrical wall I8 is a series of radially upwardly extending pin bores 2|.

The plug Il has a cylindrical Wall 23, a. rear end wall 24, and the usual shank or operating shaft for actuating the lock bolt (not shown). The cylindrical wall 23 is provided with a series of pin bores 26 positioned to register with the previously mentioned pin bores 2| in the xed lock cylinder I0.

Slidingly mounted in the matchinggpin bores 2l and 26 is an upper set of locking pins or tumblers 2l and a corresponding lower set of the locking pins or tumblers 28. The upper locking pins 21 are continuously urged downward or radially inward by suitable springs 29 in the well known manner. Preferably the lower or inner ends of the lower locking pins 28 are provided with laterally extending feet 30 that are of curved configuration as shown and terminate in points or toes 3l.

As best shown in Figure 5, the inner surface of the cylindrical wall 23 of the lock plug II is formed with suitable grooves into which the feet 38 may be lifted, there being one such groove for each of the lower locking pins 28. In like manner the circumferential surface of the circular body I 2 inside the plug I I is formed with corresponding grooves 36 into which the feet 38 may be lowered as indicated in Figure 8. The grooves 35 and 36 may be termed outer and inner grooves respectively.

It is contemplated that suitable means may be provided either to indicate when the plug II is positioned with the pin bores 26 in register with the pin bores 2| and/or to tend to maintain the plug in this relative position. By way of example, the drawings show a yielding latch means in the form of a small ball 31 mounted in a radial bore 38 in the periphery of the plug I I and urged outward by a suitable spring 39 in the bore. When the ,pin bores 26 of the plug I I register with the pin bores 2| of the cylindrical housing I8, the

' that is an extension of the radial slot 56,

the inner grooves 36 in the periphery of the circular body I2, the toes 3l of the feet extend outward across the arcuate space 44 in the path of the guard element i4 so that the guard element may slide under the feet and lift the pins with a cam action, thereby to position the feet in the outer grooves 35 of the plug II as shown in Figure 5.

For the purpose of forming a portion of the key- Way into the plug II, the circular body I2 is formed with a longitudinal radial slot 58 and preferably is also formed with an axial bore or passage 5I in communication with the slot.

The guard member I3 is rotatably mounted in the circular opening 20 in the xed lock cylinder I8 and has a radial shoulder 52 slidingly engaging the end wall I9 of the lock cylinder. The curved blade-like guard element I4 is an integral part o1" the guard member I3 and extends longitudinally inward from the shoulder 52.

The guard member I3 cooperates with the circular body I2 to form the keyway of the lock and for this purpose is formed with an axial bore or passage 55 and a longitudinal radial slot 56 extending from the axial passage almost but not quite to the periphery of the guard member. As best shown in Figure 3 the radial slot 56 is directed centrally of the guard element I4. Preferably the guard member I3 is formed with an inner extension in the form of a tubularwell 58 that extends into and is journaled by the axial bore or passage 5l in the circular body I2. As best shown in Figure 4 the tubular wall 58 which forms the inner end of the axial passage 55 has a slot 5S The portion of the guard member I3 that protrudes outward from the cylindrical housing I@ has a knurled surface 68 to serve as a convenient manually operable knob.

Figures 4 and 5 show the guard member I3 turned to what may be termed its key-receiving position relative to the circular body I2. At this position the keyway has what may be termed a key-receiving configuration, the keyway being a straight passage into which a key may be inserted.

rI'his passage comprises the two central bores or passages 5I and 55 of the circular body I2 and guard member I 3, respectively, together with the slot 5!) of the circular body in registration with the slots 58 and 53 of the guard member.

small ball 3'! yieldingly seats in a shallow latching P" recess 48 in the cylindrical housing I0, as best shown in Figure 5.

The circular body I2 is xedly secured to the plug II by two pins 43 as indicated in Figures 4 and 5 so that the plug and circular body are unitary with each other and may be regarded as constituting a single plug structure. It is contemplated that there will be suiiicient space between the circumference of the circular body I2 and the surrounding cylindrical wall 23 of the plug I i to receive the curved guard element I4 and to permit the guard element to be shifted around at least a portion of the circumference of the circular body. For this purpose the cylindrical wall 23 of the plug is cut away to provide an arcuate clearance space-44 which, as shown in Figure 5, terminates at one of its ends in a shoulder and terminates at its other end in a shoulder 45. It will be noted in Figure 8 that when the feet 30 of the locking pins 28 are Positioned in When the guard member I3 is rotated to any appreciable extent from the position shown in Figures 4 and 5 the keyway changes from the configuration of a straight passage to the configuration of a tortuous passage. For example, in Figures '7 and 8 showing the gua-rd member I3 rotated 180 from the position shown in Figures 4 and 5, the slot 56 being out of register with the slot 5i! terminates in a blank wall formed by the l end face of the circular body I2 and the tubular wall 58 extending inwardly fromthe guard member cuts off direct radial communication from the axial bore or passage of the guard member to the slot 58 in the region of the inner ends of the locking pins 58.

The portion of the keyway that remains unaffected by rotation of the guard member I3 comprises the axial bore or passage 55 through the guard member, the remaining portion of the axial bore or passage 5I in the circular body I2 and the radial slot 58 in the circular body. As best shown in Figure 7, the key 6I for use with the lock conforms to this unchanged portion of the keyway in the sense of being dimensioned to lie within the confines thereof. It will be `"f28;the"position` of the'v locking pinsz willrbe de-i vv"termined ibyfthe Y'position of the guardA element "IIL ""If' :the -guardameriiberf vI3 is at the rotary position spacing the guard element Iii away from "-thevregionvv of' the locking pins,` as showrr in Fig- "'bytheciroulan'body 'I2 With the -feet-S ofv the 3locliingl pinsv seated-iin vvthe-inner 'groovest` in the rperiphery klof the circular body. At these hlov/'erliniit `-positionsfof 'the locking' pins, the Jupper'set Lof-1ocking -pins 1v extendl from the 'cylindrical lhousing IUpartiallyintorthe plug II "thereby locking'- the plugff against rotation rela-y tive to "the `cylindrical housing.

fyon the-'otherhand'the guard member I3 "is rotated -vto -place the guard element I4 under* "the'f'locking pins,"'asfsh'own'lin"Figures 4 andl 5, withfthe -f'eet iii of if the locking pins v'-displacec upwardlyinto-theouter grooves -55 in^the plug I I;fthe"lower1set offlocking pins 28 will. extend "liridric'al" housing I El Eto lockfthe plug-against ro- .'tation=r`elative lto the cylindrical housing. Thus, `there. are tWo'-limitlockingpositions furthe two f-setslof-lockingl-pins 21 and T28. 'There is nospos- .fsibilityoff-l'the4k guardnelement I4 unlocking the fplug II-` by its cam action against "the feet t0 -raiseandi-flower theftwo sets of locking pins, -Sb'ecausethe-'abutting ends 'of 'the two sets .ofrlock- --lingf lpins-- are fistaggered* to cross theriparting line 'betweenfthe :plugh-andlthe cylindrical housing 'at "-diferenttimes. Thus,fin the 'transition between the'two'limit .locking 1=positi`ons caused bythe foamfactionffoffstheguard element III,y there is v always la-t1'. -least brief-pin.y interlocking .'the; .plug

and cylindricalhousing.

2li VVa Aperson attempting .toLpick-the lock rotates ithe Yguard-iineiriber 'I3 tov ltheV positionsh'owni in --'I1ig.ures`*41 and 53; for access `into :the .interior of fthe-ping; the guardielementi willibcautomatit -cally.positioned across .theinnerendsiof ythe locking pinsf ltheriebyi cutting lofi a'cc'essito the locking pins. 1f the guard member I3 is rotated to rem'ove'the fguardfelementilli frorn'the region of the lockingfpiirthe keywayautoniatically changes to the tortuous angular configuration shown in Figure 7 and thereby makesthe locking pins to .-all. practical purposes' 'inaccessible for unauthorizedmanip'ulation 'through 'the' keyway.

"lo unlock' the lock;"`the guard member i3 is rotated to the key receiving position shown in Figure 4 to provide a straight passage through which the key may be inserted to the operating position shown in dotted outline in Figure 4. In practice the key may be partially inserted for the purpose of rotating the guard member I3 to the key receiving position and then the inward movement of the key may be completed.

It will be noted in Figure 4 that at this time theV guard element I4 is under the locking pins and holds the locking pins at their outer limit positions. The guard member I3 isrthen rotated to the position shown in Figure '1 orV at least sufciently to carry the guard element Iii away from the feet 3U of the locking pins.

The removal of the guard element I4 from the -"-regi'on ""f ithefflocking-f LYpins f permitsA ithe`= docking pinsfitofidropffdownward `from v`their upper limit locking position under pressure from the springs -lower limiti locking positions shown in "Figure f`6 beeausethefkeytl" stops thedownward movervment 'offth locking-pins at the positions shown fin Figure '1. -lIt-'can be--seenin- Figure 7 thatithe klvinutuallycontacting` faces of the two sets of .ici-

locking pins'"21fand-28 coincide With the periph- "ery voi thee-'plugY II so that the plug `is now free to "rotate Lrelative fto the cylindrical housing IQ. The plug IImaylbe rotated to its unlocked posi- ---tionffsimply yby turning theA keyy 6 I the key turn- 'ing :the-circularibody I2 which is connected to thee-plug yI Ir bythe pins-43.

To again-luchthe lock,' the key SI is used to rotate theplug 'I I luntil the yielding latch in the form of 'theb'all` 31 seats in the latching recess 546),'V thus placing the pin bores of the plug in reg-iStratiOuWiththe corresponding pin bores 'in the cylindrical housing -I. The guard mein- `#aber :Isis-then rotated to'shift the guard element tion-shown-in vFigures 4 and 5.

-theguardfmemberl brings' the slot V55:3 in the I4 under the locking -pinsthereby lifting the Vlocking'pins to their vupper vlimit locking posi- This-rotation of 'guard-"member linto registration withthe slotl 53 in the circular body I2, thereby forming the straight passage *shown inligure 4 through which the key-*6I may be withdrawn.

vMy fdisclosure in specific detail of a preferred embodiment of the invention will suggest to those skilled in the-artV various changes, modifications,

and other idepartures from the disclosure that properly' -lie within'the spirit and scope of my appendediclaims fic Having-:described my invention,` claim:

l.-'A- lock combination comprising: a stationary lockcylinder-witha'vfirst set of radial pin bores; a first means in the form of a plug rotat- -1ablyfmountedYinsaid cylinder, said plug having a secondusetfofY radial lpin lbores positioned to register with said rst setat a locking vposition of saidf-plug'relative to vsaid cylinder, said plug f having an-axial borel andv a slot extending `radiallyv from the fbore; two sets of spring-pressed locking pins-in saidtwo sets of pin-bores respectively ya second lmeans having an axial bore and Y- a radialslot tococperate with thebore and slot of said first 'means to form a keyway into said piug,-saidifirst and' second means being adapted for relative-movement for manually varying the v`conguration of* thekeyway from a first conguration--airording relatively free access 4to the -pin bores from said-keyway when said keyway is changed to said nrst configuration.

2. A lock combination as set forth in claim 1 in which said rst and second congurations of the keyway have axial portions in common to accommodate the axial portion of a key.

3. A lock combination as set forth in claim l in which said rst configuration provides a substantially straight passage from the exterior to the region of the second set of pin bores and said second configuration provides a tortuous passage.

4. A lock combination as set forth in claim 3 which includes a key that is insertable through said straight passage but conforms to said tortuous passage.

5. A lock combination as set forth in claim 1 in which one of said first and second means has an exposed knob portion for manual manipulation.

6. A lock combination comprising: a stationary lock cylinder with a first set of radial end bores; a plug structure rotatably mounted in said cylinder, said plug structure having a second set of radial pin bores positioned to register with said iirst set, said plug structure having a rst longitudinal slot communicating with the inner ends of said second set of pin bores; springpressed locking pins in said pin bores; and a manually operable guard member rotatably mounted in said cylinder to cooperate with said plug structure to form a keyway which varies in coniiguration with rotation of the guard member relative to the plug structure, said guard member having an axial passage and a second longitudinal slot, said guard member being movable to a key-receiving position at which said second slot registers with said i'lrst slot and being movable therefrom to a second position With said second slot out of register with the iirst slot, said guard member having a guard element positioned to register with said pin bores to cut the pin bores oir from said rst slot at said keyreceiving position of the member and to be out of register with the pin bores at said second position of the member.

'7. A lock combination as set forth in claim 6 which includes a key conforming to the configuration of said keyway at said second position of the guard member.

8. A lock combination as set forth in claim 6 in which said guard member has an inner tubular Wall extending into said plug structure and forming the inner end of said passage'said tubular Wal1 having a radial slot continuing said second slot whereby said tubular Wall cuts oft a portion of said first slot at said second position of the guard member.

9. A lock combination as set forth in claim 8 in which said guard member is coaxially journaled in said plug structure. Y

10. A lock combination as set forth in claim 6 in which said guard element is a blade curved concentrically of the plug structure and in which the plug structure provides a correspondingly curved clearance space for travel of the guard ele-ment into and out oi register with said pin bores.

11. A lock combination as set forth in claim 5 which includes means to yieldingly latch said plug structure in position with said two sets of pin bores in registration with each other.

12. A iock combination as set forth in claim 6 in which includes a key; in which said locking pins in the absence of a key are free to move to inner locking positions under spring pressure when said guard element is out of register with the pin bores; in which said key is dimensioned to displace said locking pins outward from said inner locking position to intermediate release positions; and in which said guard element when in register with said bores displaces said pins to outer locking positions.

13. A lock combination as set forth in claim 6 in which said locking pins have laterally extending feet for contact with cooperating surfaces of said plug structure to limit the inner movement of the pins and said feet are shaped as cams for outward movement of the pins by said guard element.

14. A lock combination comprising a stationary lock cylinder with a rst set of radial pin bores; a plug with a cylindrical Wall rotatably mounted in said cylinder, said cylindrical Wall having a second set of radial pin lbores positioned to register with said first set; spring-pressed locking pins in said pin bores; a circular body inside said plug and xedly connected With the plug, the periphery of said body serving as a stop to limit the inward movement of said pins, said body having a longitudinal slot communicating with said second set of pin bores, said body and said cylindrical Wall of the plug forming a concentric clearance space extending at least partially around the circular body; a manually operable guard member' rotatably mounted in said cylinder coaxially thereof to cooperate with said body to form a keyWay which varies in configuration with rotation of the guard member relative to said body, said guard member having an axial passage and a second longitudinal slot extending from the passage toward the periphery of the member, said guard member being movable to a key-receiving position at which said two slots register with each other and being movable through a range of other positions with the two slots out or" register with each other but with said passage in communication with said first slot, said guard member having a concentrically curved guard blade in said space positioned to cut off said pin bores when the member moves out of said range of positions into said key-receiving position.

15. A lock combination as set forth in claim 14 in which said locking pins have cam elements both for contact with said body and for cooperation with said blade and in which grooves are provided both in said body and in said cylindrical Wall to receive said cam elements.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 321,306 Markham June 30, 1885 2,179,947 Miller Nov. 14, 1939 2,552,012 OKane May 8, 1951 

